1991 07/26 CA Gifford Keeth -Bell 206

Incident Name: small holdover lightning fire — the Pine Fire — on the Stanislaus National Forest
Date: 7/26/91, about 1700 hours
Personnel: Gifford Keeth
Age: 58
Agency/Organization: Rogers Helicopters of Clovis, under contract to the Forest Service
Position: pilot

Summary: During a landing approach out of ground effect, the Bell 206 helicopter descended into the viortices created by the main rotor blades and lost main rotor lift. The helicoter descended, struck trees and impacted nose down, killing Giff.

Maps

“one mile north of Lake Alpine, Stanislaus National Forest”

Very General Incident Location

{mosmap lat=’38.492862’|lon=’-119.999275’|marker=’0’|text=’one mile north of Lake Alpine, Stanislaus National Forest’}

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Reports, Documentation, Lessons Learned

Concise Information from the NTSB, FAA, USFS, WFF and research by the WLF Staff:
- July 26, 1991
- 1 killed: Gifford Keeth
- Operator: Rogers Helicopters of Clovis under contract with the US Forest Service
- Type: Bell BHT-206L1
- Location: north of Alpine Lake, Stanislaus National Forest
- FAA Registration # N523RR
- NTSB # LAX91TL#08
National Transportation Safety Board did not investigate this incident.
Forest Service Investigations – Fatal Aviation Accident History (1974-2002): Pages 67-68 for this incident (364 K pdf) | Entire History (download 4.72 MB pdf)
Forest Service Investigation Probable Cause:

In developing a probable cause to this mishap, the investigation team stated that the flight profile of the final approach to land the load in the opening was conducive to the helicopter entering into a main rotor vortex ring state that was aggravated by a shift in direction or down draft in the wind. This could have caused a descent beyond the pilot’s capability to arrest in the vertical space available to perform an escape maneuver. They deemed the mishap was caused by the strike of the main rotor blade near the top of a tree.
NTSB online lookup Utility # LAX91TL#08
Note: Prior to 1996 NTSB did not investigate Gov owned and operated, Gov owned and contractor operated or some aircraft that were privately owned and operated as “public aircraft”. Government agency investigations and reports were/are often hard to find and access. The “Pressler Act”, passed in 1995 and enacted in 1996, changed that, making all aircraft accident reports easier to access and lessons easier to learn. (Click the link and search on “Pressler”.)
Flight Safety Foundation (flightsafety.org): Flight Safety Digest, Vol 25, No. 6, Nov-Dec 1999, Rotor Wing Accidents 1974-1998 (102 K pdf)
USFS Heroes: Gifford Keeth
USFA Memorial Database: Gifford O. Keeth